Magnetic tunneling junction devices, memories, memory systems, and electronic devices

ABSTRACT

Provided is a magnetic tunneling junction device including a first structure including a magnetic layer; a second structure including at least two extrinsic perpendicular magnetization structures, each including a magnetic layer and; a perpendicular magnetization inducing layer on the magnetic layer; and a tunnel barrier between the first and second structures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/398,640, filed on Feb. 16, 2012, which claims priority under 35U.S.C. §119 to Korean Patent Application No. 10-2011-0079627, filed onAug. 10, 2011, in the Korean Intellectual Property Office, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Embodiments of inventive concepts relate generally to semiconductormemory devices. For example, embodiments of inventive concepts relate tosemiconductor memory devices including magnetic tunneling junctiondevices, memories, memory systems, and electronic devices.

With increasing use of portable computing devices and wirelesscommunication devices, memory devices may require higher density, lowerpower, and/or nonvolatile properties. Magnetic memory devices may beable to satisfy the aforementioned technical requirements.

An example data storing mechanism for a magnetic memory device is atunnel magneto resistance (TMR) effect of a magnetic tunnel junction(MTJ). For example, a magnetic memory device with a MTJ have beendeveloped such that an MTJ may have a TMR ratio of several hundred toseveral thousand percent. However, as pattern dimensions are reduced, itmay become more difficult to provide a thermally stable MTJ.

SUMMARY

Embodiments of inventive concepts provide magnetic memory devices havingimproved thermal stability.

According to example embodiments of inventive concepts a magnetictunneling junction device may include a first structure including amagnetic layer; a second structure including at least two extrinsicperpendicular magnetization structures, each including a magnetic layerand; a perpendicular magnetization inducing layer on the magnetic layer;and a tunnel barrier between the first and second structures.

In example embodiments, the second structure further includingadditional extrinsic perpendicular magnetization structures, eachincluding a magnetic layer and; a perpendicular magnetization inducinglayer on the magnetic layer.

In example embodiments, the magnetic tunneling junction further includesa perpendicular magnetization preserving layer on one of theperpendicular magnetization inducing layers.

In example embodiments, each magnetic layer has an oxygen affinity lessthan each perpendicular magnetization inducing layer.

In example embodiments, each perpendicular magnetization preservinglayer has an oxygen affinity less than each perpendicular magnetizationinducing layer.

In example embodiments, the magnetic layers are made of a ferromagneticmaterial.

In example embodiments, the ferromagnetic material is at least one ofCoFeB, CoFe, NiFe, CoFePt, CoFePd, CoFeCr, CoFeTb, CoFeGd or CoFeNi.

In example embodiments, the magnetic layers have a thickness in a rangeof about 1 angstrom to about 30 angstroms.

In example embodiments, the magnetic layers have a thickness in a rangeof about 3 angstroms to about 17 angstroms.

In example embodiments, the perpendicular magnetization inducing layersare in direct contact with the magnetic layers.

In example embodiments, the perpendicular magnetization inducing layersare an oxygen-containing material.

In example embodiments, the perpendicular magnetization inducing layersare a metal oxide.

In example embodiments, the metal oxide is at least one of magnesiumoxide, tantalum oxide, titanium oxide, aluminum oxide, magnesium zincoxide, hafnium oxide, or magnesium boron oxide.

In example embodiments, the perpendicular magnetization inducing layersinclude at least one of Ta, Ti, U, Ba, Zr, Al, Sr, Hf, La, Ce, Sm, Mg,Th, Ca, Sc, or Y.

In example embodiments, the perpendicular magnetization inducing layershave an electrical resistivity higher than the magnetic layers or theperpendicular magnetization preserving layer.

In example embodiments, the perpendicular magnetization inducing layershave a thickness less than the magnetic layers or the perpendicularmagnetization preserving layer.

In example embodiments, the perpendicular magnetization preserving layerhas an electrical resistivity lower than the perpendicular magnetizationinducing layers.

In example embodiments, the perpendicular magnetization preserving layeris formed of at least one noble metal or copper.

In example embodiments, the at least one noble metal includes ruthenium(Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium(Ir), platinum (Pt), or gold (Au).

In example embodiments, the perpendicular magnetization preserving layeris formed of at least one of material having an electrical resistivitylower than tantalum or titanium.

In example embodiments, the magnetic tunneling junction further includesa substrate; wherein the first structure is a lower structure closer tothe substrate and the wherein the second structure is an upper structurefurther from the substrate.

In example embodiments, the magnetic layers of the second structure arefree magnetic layers.

In example embodiments, the first structure includes fixed magneticlayers.

In example embodiments, the magnetic tunneling junction further includesa top electrode on the perpendicular magnetization preserving layer.

In example embodiments, the magnetic tunneling junction further includesa substrate; wherein the first structure is an upper structure furtherfrom the substrate and the wherein the second structure is a lowerstructure closer to the substrate.

In example embodiments, the first structure includes at least twoextrinsic perpendicular magnetization structures, each including amagnetic layer and a perpendicular magnetization inducing layer on themagnetic layer, a metal layer between two of the perpendicularmagnetization inducing layer, and a perpendicular magnetizationpreserving layer on one of the perpendicular magnetization inducinglayers.

In example embodiments, a number of the at least two extrinsicperpendicular magnetization structures in the first structure is greaterthan a number of the at least two extrinsic perpendicular magnetizationstructures in the second structure.

According to example embodiments of inventive concepts an electronicdevice, may include a bus; a wireless interface configured to transmitdata to or receive data from a wireless communication network connectedto the bus; an I/O device connected to the bus; a controller connectedto the bus; and a memory including a semiconductor device including amagnetic tunneling junction device, connected to the bus, configured tostore a command code to be used by the controller or user data.

According to example embodiments of inventive concepts a memory systemmay include a memory device including a semiconductor device including amagnetic tunneling junction device, for storing data; and a memorycontroller configured to control the memory device to read data storedin the memory device or to write data into the memory device in responseto a read/write request of a host.

According to example embodiments of inventive concepts a magnetictunneling junction device may include a first structure including afixed magnetic layer; a tunnel barrier on the first structure; a secondstructure on the tunnel barrier, the second structure including a firstmagnetic layer on the tunnel barrier, a first perpendicularmagnetization inducing layer on the first magnetic layer, an exchangecoupling layer on the first perpendicular magnetization inducing layer,a second perpendicular magnetization inducing layer on the exchangecoupling layer, a second magnetic layer on the second perpendicularmagnetization inducing layer, a third perpendicular magnetizationinducing layer on the second magnetic layer.

In example embodiments, the magnetic tunneling junction device furtherincludes a perpendicular magnetization preserving layer on the thirdperpendicular magnetization inducing layer; and

In example embodiments, each magnetic layer has an oxygen affinity lessthan each perpendicular magnetization inducing layer.

In example embodiments, each perpendicular magnetization preservinglayer has an oxygen affinity less than each perpendicular magnetizationinducing layer.

In example embodiments, the perpendicular magnetization inducing layersare a metal oxide.

In example embodiments, the metal oxide is at least one of magnesiumoxide, tantalum oxide, titanium oxide, aluminum oxide, magnesium zincoxide, hafnium oxide, or magnesium boron oxide.

In example embodiments, the perpendicular magnetization inducing layersinclude at least one of Ta, Ti, U, Ba, Zr, Al, Sr, Hf, La, Ce, Sm, Mg,Th, Ca, Sc, or Y.

In example embodiments, the perpendicular magnetization inducing layershave an electrical resistivity higher than the magnetic layers or theperpendicular magnetization preserving layer.

In example embodiments, the perpendicular magnetization inducing layershave a thickness less than the magnetic layers or the perpendicularmagnetization preserving layer.

In example embodiments, the magnetic tunneling junction further includesa substrate; wherein the first structure is a lower structure closer tothe substrate and the wherein the second structure is an upper structurefurther from the substrate.

In example embodiments, the magnetic layers of the second structure arefree magnetic layers.

In example embodiments, the first structure including fixed magneticlayers.

In example embodiments, the magnetic tunneling junction further includesa top electrode on the perpendicular magnetization preserving layer.

In example embodiments, the magnetic tunneling junction further includesa substrate; wherein the first structure is an upper structure furtherfrom the substrate and the wherein the second structure is a lowerstructure closer to the substrate.

According to example embodiments of inventive concepts an electronicdevice, may include a bus; a wireless interface configured to transmitdata to or receive data from a wireless communication network connectedto the bus; an I/O device connected to the bus; a controller connectedto the bus; and a memory including a semiconductor device including amagnetic tunneling junction device, connected to the bus, configured tostore a command code to be used by the controller or user data.

According to example embodiments of inventive concepts a memory systemmay include a memory device including a semiconductor device including amagnetic tunneling junction device, for storing data; and a memorycontroller configured to control the memory device to read data storedin the memory device or to write data into the memory device in responseto a read/write request of a host.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingbrief description taken in conjunction with the accompanying drawings.The accompanying drawings represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is a schematic circuit diagram of a unit cell of a magneticmemory device according to example embodiments of inventive concepts;

FIGS. 2 through 6 are circuit diagrams exemplarily illustratingselection devices according to example embodiments of inventiveconcepts;

FIG. 7 is a diagram schematically illustrating a first type of MTJaccording to example embodiments of inventive concepts;

FIG. 8 is a diagram schematically illustrating a second type of MTJaccording to example embodiments of inventive concepts;

FIGS. 9 through 17 are sectional views exemplarily illustrating layeredstructures that may be used as a portion of the magnetic tunnel junctionMTJ;

FIGS. 18A and 18B are graphs illustrating some aspects of an extrinsicperpendicular magnetization structure;

FIG. 19 is a graph illustrating other aspects of an extrinsicperpendicular magnetization structure;

FIG. 20 is a diagram presented to describe still other aspects of anextrinsic perpendicular magnetization structure;

FIG. 21 is an experimental graph exemplarily showing some magneticproperties of an MTJ according to example embodiments of inventiveconcepts;

FIG. 22 is a sectional view exemplarily showing the first type ofmagnetic tunnel junction according to example embodiments of inventiveconcepts;

FIG. 23 is a sectional view exemplarily showing the second type ofmagnetic tunnel junction according to example embodiments of inventiveconcepts;

FIG. 24 is a schematic circuit diagram of a unit cell of a magneticmemory device according to example embodiments of inventive concepts;and

FIGS. 25 and 26 are schematic block diagrams schematically illustratingelectronic devices including a semiconductor device according to exampleembodiments of inventive concepts.

It should be noted that these figures are intended to illustrate thegeneral characteristics of methods, structure and/or materials utilizedin certain example embodiments and to supplement the written descriptionprovided below. These drawings are not, however, to scale and may notprecisely reflect the precise structural or performance characteristicsof any given embodiment, and should not be interpreted as defining orlimiting the range of values or properties encompassed by exampleembodiments. For example, the relative thicknesses and positioning ofmolecules, layers, regions and/or structural elements may be reduced orexaggerated for clarity. The use of similar or identical referencenumbers in the various drawings is intended to indicate the presence ofa similar or identical element or feature.

DETAILED DESCRIPTION

Example embodiments of inventive concepts will now be described morefully with reference to the accompanying drawings, in which exampleembodiments are shown. Example embodiments of inventive concepts may,however, be embodied in many different forms and should not be construedas being limited to example embodiments set forth herein; rather, theseexample embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the concept of exampleembodiments to those of ordinary skill in the art. In the drawings, thethicknesses of layers and regions are exaggerated for clarity. Likereference numerals in the drawings denote like elements, and thus theirdescription will be omitted.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Like numbers indicate like elementsthroughout. As used herein the term “and/or” includes any and allcombinations of one or more of the associated listed items. Other wordsused to describe the relationship between elements or layers should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” “on” versus “directlyon”).

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising”, “includes” and/or “including,” if usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Example embodiments of inventive concepts are described herein withreference to cross-sectional illustrations that are schematicillustrations of idealized embodiments (and intermediate structures) ofexample embodiments. As such, variations from the shapes of theillustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, example embodiments ofinventive concepts should not be construed as limited to the particularshapes of regions illustrated herein but are to include deviations inshapes that result, for example, from manufacturing. For example, animplanted region illustrated as a rectangle may have rounded or curvedfeatures and/or a gradient of implant concentration at its edges ratherthan a binary change from implanted to non-implanted region. Likewise, aburied region formed by implantation may result in some implantation inthe region between the buried region and the surface through which theimplantation takes place. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe actual shape of a region of a device and are not intended to limitthe scope of example embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments of inventiveconcepts belong. It will be further understood that terms, such as thosedefined in commonly-used dictionaries, should be interpreted as having ameaning that is consistent with their meaning in the context of therelevant art and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

According to example embodiments of inventive concepts, a magneticmemory device may be configured to include an extrinsic perpendicularmagnetization structure, which will be in more detail below. Inaddition, Korean Patent Application Nos. 2011-0024429, filed on Mar. 18,2011, and 2011-0074500, filed on Jul. 28, 2011 disclose technicalfeatures related to the extrinsic perpendicular magnetization structure.The entire contents disclosed in Korean Patent Application Nos.2011-0024429 and 2011-0074500 are hereby incorporated by reference intheir entirety.

FIG. 1 is a circuit diagram exemplarily illustrating a unit cell ofmagnetic memory devices according to example embodiments of inventiveconcepts.

Referring to FIG. 1, a unit cell 100 may be disposed between first andsecond interconnection lines 10 and 20 crossing each other. The unitcell 100 may be connected in series to the first and secondinterconnection lines 10 and 20. The unit cell 100 may include aselection element 30 and a magnetic tunnel junction MTJ. The selectionelement 30 and the magnetic tunnel junction MTJ may be electricallyconnected in series to each other. In some example embodiments, one ofthe first and second interconnection lines 10 and 20 may be used as aword line, and the other may be used as a bit line.

The selection element 30 may be configured to selectively control anelectric current passing through the magnetic tunnel junction MTJ. Forexample, as shown in FIGS. 2 through 6, the selection element 30 may beone of a diode, a pnp bipolar transistor, an npn bipolar transistor, anNMOS field effect transistor (FET), and a PMOS FET. In the case that theselection element 30 is a three-terminal switching device, such as abipolar transistor and/or MOSFET, an additional interconnection line(not shown) may be connected to the selection element 30.

The magnetic tunnel junction MTJ may include a lower structure 41, anupper structure 42, and a tunnel barrier 50 therebetween. Each of thelower and upper structures 41 and 42 may include at least one magneticlayer, which is formed of a magnetic material.

One of the magnetic layers may be configured to have a fixedmagnetization direction, which is not changed by an external magneticfield generated under usual circumstances. Hereinafter, for conveniencein description, a term ‘pinned layer PL’ will be used to represent themagnetic layer having the fixed magnetization property. By contrast, theother of the magnetic layers may be configured to have a magnetizationdirection being switchable by an external magnetic field appliedthereto. Hereinafter, a term ‘free layer FRL’ will be used to representthe magnetic layer having the switchable magnetization property. Thatis, as shown in FIGS. 7 and 8, the magnetic tunnel junction MTJ mayinclude at least one free layer FRL and at least one pinned layer PL,which are separated by the tunnel barrier 50.

Electrical resistance of the magnetic tunnel junction MTJ may besensitive to a relative orientation of magnetization directions of thefree and pinned layers FRL and PL. For example, the electricalresistance of the magnetic tunnel junction MTJ may be far greater whenthe relative orientation is antiparallel than when parallel. This meansthat the electrical resistance of the magnetic tunnel junction MTJ maybe controlled by changing the magnetization direction of the free layerFRL. The magnetic memory devices according to example embodiments ofinventive concepts may be realized based on this data storing mechanism.

As shown in FIGS. 7 and 8, the lower and upper structures 41 and 42 ofthe magnetic tunnel junction MTJ may be sequentially formed on asubstrate SUB. In example embodiments, according to a relativeconfiguration between the free layer FRL and the substrate SUB or aforming order of the free layer FRL and the pinned layer PL, themagnetic tunnel junction MTJ may be, for example, classified into twotypes: (a) a first type of magnetic tunnel junction MTJ1 configured insuch a way that the lower and upper structures 41 and 42 include thepinned layer PL and the free layer FRL, respectively, as shown in FIG.7, and (b) a second type of magnetic tunnel junction MTJ2 configured insuch a way that the lower and upper structures 41 and 42 include thefree layer FRL and the pinned layer PL, respectively, as shown in FIG.8.

FIGS. 9 through 17 are sectional views exemplarily illustrating layeredstructures that may be used as a portion of the magnetic tunnel junctionMTJ. That is, each of the lower and upper structures 41 and 42 of themagnetic tunnel junction MTJ may be configured to include one of thelayered structures, which will be exemplarily described with referenceto FIGS. 9 through 17. In example embodiments where the layeredstructures of FIGS. 9 through 17 are used as a portion of the lowerstructure 41, they may be provided as an inverted structure (e.g., in amanner reversed to those shown in FIGS. 9 through 17).

According to example embodiments of inventive concepts, at least one ofthe lower and upper structures 41 and 42 may be configured to includeall or part of an extrinsic perpendicular magnetization structure(EPMS), which will be exemplarily described with reference to FIGS. 9through 15. For example, the lower structure 41 may be configured toinclude all or part of one of the extrinsic perpendicular magnetizationstructures EPMS, which will be described with reference to FIGS. 9through 15, and the upper structure 42 may be configured to include allor part of one of intrinsic perpendicular magnetization structures(IPMS), which will be exemplarily described with reference to FIGS. 16and 17. Alternatively, the lower structure 41 may be configured toinclude all or part of one of the intrinsic perpendicular magnetizationstructures (IPMS), which will be exemplarily described with reference toFIGS. 16 and 17, and the upper structure 42 may be configured to includeall or part of one of the extrinsic perpendicular magnetizationstructures EPMS, which will be described with reference to FIGS. 9through 15. Furthermore, in some example embodiments, both of the lowerand upper structures 41 and 42 may be configured to include all or partof one of the extrinsic perpendicular magnetization structures EPMS,which will be described with reference to FIGS. 9 through 15.

Referring to FIGS. 9 through 15, the extrinsic perpendicularmagnetization structure EPMS may include at least one magnetic layer MGLand/or at least one perpendicular magnetization inducing layer PMIcovering the magnetic layer MGL. Here, the magnetic layer MGL of theextrinsic perpendicular magnetization structure EPMS may be used as themagnetic layer constituting the lower structure 41 and/or the upperstructure 42. In other words, the free layer FRL or the pinned layer PLmay be realized using the magnetic layer MGL of the extrinsicperpendicular magnetization structure EPMS.

In the extrinsic perpendicular magnetization structure EPMS, themagnetic layer MGL may include a ferromagnetic material. For example,the magnetic layer MGL may be formed of at least one of CoFeB, CoFe,NiFe, CoFePt, CoFePd, CoFeCr, CoFeTb, CoFeGd or CoFeNi. According tosome aspects of inventive concepts, the magnetic layer MGL may be anintrinsic horizontal magnetic layer exhibiting an intrinsic horizontalmagnetization property. In more detail, owing to magnetic anisotropycaused by the geometrical shape of the magnetic layer MGL, the magneticlayer MGL (e.g., of CoFeB) may have a magnetization direction confinedto a plane (e.g., xy-plane) parallel to a main surface thereof. (Here,the term ‘main surface’ represents a surface of the magnetic layer MGLhaving the largest area and, in most cases, may be a top or bottomsurface of the magnetic layer MGL.) The term ‘intrinsic horizontalmagnetization property’ represents this geometry-dependent horizontalmagnetic anisotropy. The afore-exemplified ferromagnetic materials mayexhibit this intrinsic horizontal magnetization property.

In addition, the magnetic layer MGL may be provided in a form of thinpattern, whose vertical thickness is far smaller than horizontal lengthsthereof. In example embodiments, for the extrinsic perpendicularmagnetization structure EPMS, a thickness of the respective magneticlayers MGL may be in a range of about 1 angstrom to about 30 angstroms.In more specific embodiments, the thickness of the respective magneticlayers MGL may be in a range of about 3 angstroms to about 14 or toabout 17 angstroms.

The perpendicular magnetization inducing layer PMI may be formed to bein direct contact with the magnetic layer MGL, and this directlycontacting configuration enables to change a magnetization direction ofthe magnetic layer MGL from parallel to perpendicular to the mainsurface of the magnetic layer MGL. That is, the perpendicularmagnetization inducing layer PMI may serve as an external factor causingthe perpendicular magnetization property for the magnetic layer MGLhaving the intrinsic perpendicular magnetization property. In thissense, the perpendicular magnetization inducing layer PMI and themagnetic layer MGL being in contact with each other may constitute amagnetic structure with an extrinsic perpendicular magnetizationproperty (e.g., the extrinsic perpendicular magnetization structure).Hereinafter, the magnetic layer MGL in the extrinsic perpendicularmagnetization structure may be called “an extrinsic perpendicularmagnetic (EPM) layer”.

The perpendicular magnetization inducing layer PMI may be anoxygen-containing material. In some example embodiments, theperpendicular magnetization inducing layer PMI may be at least one metaloxide. For example, the perpendicular magnetization inducing layer PMImay be at least one of magnesium oxide, tantalum oxide, titanium oxide,aluminum oxide, magnesium zinc oxide, hafnium oxide, or magnesium boronoxide, but example embodiments of inventive concepts may not be limitedthereto. In example embodiments, the perpendicular magnetizationinducing layer PMI may have electrical resistivity higher than themagnetic layer MGL. In example embodiments, an electric resistance ofthe magnetic tunnel junction MTJ may be strongly dependent on theelectrical resistivity of the perpendicular magnetization inducing layerPMI. In order to reduce this dependency, the perpendicular magnetizationinducing layer PMI may be formed to be thin. For example, theperpendicular magnetization inducing layer PMI may be formed to have athickness less than the magnetic layer MGL. In some example embodiments,the perpendicular magnetization inducing layer PMI may have a thicknessof about 1 angstrom to about 15 angstroms.

In some example embodiments, as exemplarily shown in FIG. 9, theextrinsic perpendicular magnetization structure EPMS may include themagnetic layer MGL and the perpendicular magnetization inducing layerPMI, each of which is provided in a single-layered structure.

In other example embodiments, as exemplarily shown in FIGS. 10 through15, the extrinsic perpendicular magnetization structure EPMS may includethe magnetic layers MGL provided as a multi-layered structure and theperpendicular magnetization inducing layers PMI provided as amulti-layered structure. The magnetic layers MGL and the perpendicularmagnetization inducing layers PMI may be alternatingly stacked. Forinstance, at least one the perpendicular magnetization inducing layerPMI may be interposed between the magnetic layers MGL. In exampleembodiments, the extrinsic perpendicular magnetization structure EPMSmay be configured in such a way that one perpendicular magnetizationinducing layer PMI, as shown in FIGS. 10 and 11, or two perpendicularmagnetization inducing layers PMI, as shown in FIGS. 13 and 14, may beinterposed between the magnetic layers MGL adjacent to each other.

In extrinsic perpendicular magnetization structures EPMS with themagnetic layers MGL provided as a multi-layered structure, the magneticlayers MGL may have substantially the same thickness and/or material aseach other. However, in other example embodiments, at least two of themagnetic layers MGL may differ from each other in terms of thicknessand/or material. Similarly, in some example embodiments, theperpendicular magnetization inducing layers PMI may have substantiallythe same thickness and/or material as each other. However, in otherexample embodiments, at least two of the perpendicular magnetizationinducing layers PMI may differ from each other in terms of thicknessand/or material. In example embodiments, all the magnetic layers MGL andall the perpendicular magnetization inducing layers PMI are formed tohave the substantially same material and thickness as those exemplarilydescribed above.

In addition, the extrinsic perpendicular magnetization structure EPMSmay further include at least one metal layer covering the perpendicularmagnetization inducing layer PMI. For example, the extrinsicperpendicular magnetization structure EPMS may further include aperpendicular magnetization preserving layer PMP. In some exampleembodiments, the perpendicular magnetization preserving layer PMP may beused as the uppermost or lowermost layer of the extrinsic perpendicularmagnetization structure EPMS, as exemplarily shown in FIGS. 9 through15. In some example embodiments, at least one of the perpendicularmagnetization inducing layers PMI may be interposed between theperpendicular magnetization preserving layer PMP and the magnetic layerMGL adjacent thereto. In example embodiments, a top electrode may be onthe perpendicular magnetic preserving layer PMP.

The perpendicular magnetization preserving layer PMP may be formed of amaterial having resistivity lower than the perpendicular magnetizationinducing layer PMI. For example, the perpendicular magnetizationpreserving layer PMP may be formed of at least one of noble metals, forexample, ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag),osmium (Os), iridium (Ir), platinum (Pt), or gold (Au)) or copper.According to some example embodiments of inventive concepts, theperpendicular magnetization preserving layer PMP may be formed of atleast one of materials having resistivity lower than tantalum ortitanium.

In addition, according to some aspects of inventive concepts, a portionof the perpendicular magnetization preserving layer PMP, which is incontact with the perpendicular magnetization inducing layer PMI, may beformed of a material hardly reacting with oxygen atoms. The noble metalsor copper described above may be selected as a material satisfying thisrequirement for the perpendicular magnetization preserving layer PMP. Insome example embodiments, the perpendicular magnetization preservinglayer PMP may be formed of a material hardly reacting with oxygen atoms,even during subsequent process steps or under normal operatingconditions.

In some example embodiments, the extrinsic perpendicular magnetizationstructure EPMS may further include at least one exchange coupling layerECL interposed between the magnetic layers MGL, as exemplarily shown inFIGS. 13 through 15. The exchange coupling layer ECL may be formed ofone of noble metals, for example, ruthenium (Ru), rhodium (Rh),palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt),or gold (Au).

A pair of the magnetic layers MGL, which are disposed adjacent to eachother, may exhibit a parallel or antiparallel magnetization property,according to a material and a thickness of the exchange coupling layerECL. In some example embodiments, the exchange coupling layer ECL may beconfigured in such a way that the pair of the magnetic layers MGLdisposed adjacent to each other exhibit a parallel magnetizationproperty. For instance, the exchange coupling layer ECL may be aruthenium layer having a thickness of about 2 angstrom to about 10angstroms. In example embodiments, the magnetic tunnel junction MTJ canbe operated with improved stability, such as a stepwise profile inmagnetic moment hysteresis curve. However, example embodiments ofinventive concepts may not be limited to the embodiments configured torealize the parallel magnetization property.

As shown in FIGS. 13 and 14, the perpendicular magnetization inducinglayer PMI may be provided between the exchange coupling layer ECL andone of the magnetic layers MGL adjacent thereto. For example, both oftop and bottom surfaces of the exchange coupling layer ECL may becovered with the perpendicular magnetization inducing layers PMI. Inexample embodiments, in the extrinsic perpendicular magnetizationstructure EPMS, the layer number of the perpendicular magnetizationinducing layers PMI may be greater than that of the magnetic layers MGL.However, in other example embodiments, as shown in FIG. 15, at least oneof the top and bottom surfaces of the exchange coupling layer ECL may bein direct contact with the magnetic layer MGL.

In some example embodiments, the number of the exchange coupling layersECL may be smaller by two or more than that of the magnetic layers MGL.This means that the exchange coupling layer ECL need not be disposed(but may be) at all interlayered spaces provided between the magneticlayers MGL. For example, as exemplarily shown in FIG. 15, theperpendicular magnetization inducing layer PMI or the exchange couplinglayer ECL may be singly interposed between the magnetic layers MGL.

The extrinsic perpendicular magnetization structure EPMS may furtherinclude at least one metal layer MTL covering the perpendicularmagnetization inducing layer PMI. For example, the metal layer MTL maybe provided between the magnetic layer MGL and the perpendicularmagnetization inducing layer PMI, as shown in FIG. 12. In some exampleembodiments, the metal layer MTL may be configured in such a way that itcan serve as the perpendicular magnetization preserving layer PMP. Forinstance, the metal layer MTL may be formed of a material hardlyreacting with oxygen atoms. For example, the metal layer MTL may beformed of at least one of noble metal or copper. In other exampleembodiments, the metal layer MTL may be configured in such a way that itcan serve as the exchange coupling layer ECL. That is, the metal layerMTL may be configured in such a way that a pair of the magnetic layersMGL disposed adjacent to top and bottom surfaces of the metal layer MTLexhibit a parallel or antiparallel magnetization property.

According to example embodiments of inventive concepts, one of the lowerand upper structures 41 and 42 may be configured to include an intrinsicperpendicular magnetization structure IPMS depicted in FIGS. 16 and 17.

Referring to FIGS. 16 and 17, the intrinsic perpendicular magnetizationstructure IPMS may include at least one intrinsic perpendicular magneticlayer IPML. The intrinsic perpendicular magnetic layer IPML of theintrinsic perpendicular magnetization structure IPMS may be used as themagnetic layer constituting the lower structure 41 and/or the upperstructure 42. In other words, the free layer FRL or the pinned layer PLmay be realized using the intrinsic perpendicular magnetic layer IPML.

The intrinsic perpendicular magnetic layer IPML may be formed of amaterial exhibiting an intrinsic perpendicular magnetization property.In other words, the intrinsic perpendicular magnetic layer IPML may beconfigured to have the perpendicular magnetization property, even whenthere is no external inducing element, such as the perpendicularmagnetization inducing layer PMI of the extrinsic perpendicularmagnetization structure EPMS.

For example, the intrinsic perpendicular magnetic layer IPML may includeat least one of a) CoFeTb, in which the relative content of Tb is 10% ormore, b) CoFeGd, in which the relative content of Gd is 10% or more, c)CoFeDy, d) FePt with the L1₀ structure, e) FePd with the L1₀ structure,f) CoPd with the L1₀ structure, g) CoPt with the L1₀ structure, h) CoPtwith the hexagonal close packing (HCP) structure, i) alloys containingat least one of materials presented in items of a) to h), or j) amulti-layered structure including magnetic and non-magnetic layersalternatingly stacked. The multi-layered structure including thealternatingly-stacked magnetic and non-magnetic layers may include atleast one of (Co/Pt)n, (CoFe/Pt)n, (CoFe/Pd)n, (CoP)n, (Co/Ni)n,(CoNi/Pt)n, (CoCr/Pt)n, or (CoCr/Pd)n, where the subscript n denotes thestacking number.

In more detail, as shown in FIG. 16, the intrinsic perpendicularmagnetization structure IPMS may include the intrinsic perpendicularmagnetic layer IPML having a single-layered structure and a cappinglayer CPL. The capping layer CPL may serve as a capping element capableof protecting the intrinsic perpendicular magnetic layer IPMLthereunder. The capping layer CPL may be formed of at least one ofruthenium (Ru), tantalum (Ta), palladium (Pd), titanium (Ti), platinum(Pt), silver (Ag), gold (Au), or copper (Cu).

In some example embodiments, the intrinsic perpendicular magnetizationstructure IPMS shown in FIG. 16 may be provided as an inverted structureto constitute the lower structure 41. In example embodiments, thecapping layer CPL may serve as a seed layer for growing the intrinsicperpendicular magnetic layer IPML thereon. For instance, when theintrinsic perpendicular magnetic layer IPML is formed of a material withL1₀ structure, the capping layer CPL may include a conductive metalnitride layer with the sodium chloride crystal structure (e.g., oftitanium nitride, tantalum nitride, chromium nitride, or vanadiumnitride).

Referring to FIG. 17, the intrinsic perpendicular magnetizationstructure IPMS may include a pair of the intrinsic perpendicularmagnetic layers IPML and an exchange coupling layer ECL interposedtherebetween. The exchange coupling layer ECL may be formed of one ofnoble metals, such as, ruthenium (Ru), rhodium (Rh), palladium (Pd),silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), or gold (Au).Similar to the example embodiments described with reference to FIGS. 13through 15, the pair of the intrinsic perpendicular magnetic layersIPML, which are disposed adjacent to each other, may exhibit a parallelor antiparallel magnetization property, according to a material and athickness of the exchange coupling layer ECL. In some exampleembodiments, the exchange coupling layer ECL of the intrinsicperpendicular magnetization structure IPMS may be configured in such away that the intrinsic perpendicular magnetic layers IPML exhibit theantiparallel magnetization property (e.g., synthetic antiferromagnetic(SAF) property).

FIGS. 18A and 18B are graphs illustrating some aspects of the extrinsicperpendicular magnetization structure according to example embodimentsof inventive concepts. As described above, the perpendicularmagnetization preserving layer PMP may be formed of a material hardlyreacting with oxygen atoms, even during subsequent process steps orunder normal operating conditions.

For example, as shown in FIG. 18A, the perpendicular magnetizationpreserving layer PMP may be a material having an oxygen affinity lessthan metallic elements constituting the perpendicular magnetizationinducing layer PMI. The oxygen affinity may be represented by thestandard enthalpy of reaction for the formation of metal oxide (ΔH0f[kJ/mole Oxygen]), as shown in FIG. 18B. In some example embodiments,the standard enthalpy of reaction ΔH0f of the metallic elementsconstituting the perpendicular magnetization inducing layer PMI may beless than about −500 [kJ/mole Oxygen], and the standard enthalpy ofreaction ΔH⁰ _(f) of the perpendicular magnetization preserving layerPMP may be greater than −300 [kJ/mole Oxygen]. That is, the standardenthalpy of reaction may be greater for the metallic elementsconstituting the perpendicular magnetization inducing layer PMI than forthe perpendicular magnetization preserving layer PMP, in terms of theabsolute value. In some example embodiments, the metallic elementsconstituting the perpendicular magnetization inducing layer PMI may beat least one of Ta, Ti, U, Ba, Zr, Al, Sr, Hf, La, Ce, Sm, Mg, Th, Ca,Sc, or Y, and the perpendicular magnetization preserving layer PMP mayinclude at least one of Au, Ag, Pt, Pd, Rh, Ru, Cu, Re, or Pb. As shownin FIG. 18A or 18B, the magnetic layer MGL may be formed of a materialhaving an oxygen affinity less than the metallic elements constitutingthe perpendicular magnetization inducing layer PMI and greater than theperpendicular magnetization preserving layer PMP. Further, chemicalreactivity with oxygen can be represented by various physicalquantities. For example, physical quantities, such as an oxidationpotential or a free energy in oxidation, can be used to quantitativelyrepresent the chemical reactivity with oxygen, instead of the oxygenaffinity or the standard enthalpy of reaction.

FIG. 19 is a graph illustrating other aspects of the extrinsicperpendicular magnetization structure.

Referring to FIG. 19, the extrinsic perpendicular magnetization propertymay result from a chemical combination of atoms in the magnetic layerMGL and oxygen atoms in the perpendicular magnetization inducing layerPMI. In example embodiments, as shown in FIG. 19, a transition regionTR, whose oxygen content is higher than the magnetic layer MGL and lowerthan the perpendicular magnetization inducing layer PMI, may be formedbetween the magnetic layer MGL and the perpendicular magnetizationinducing layer PMI. In some example embodiments, there is no reason thatthe oxygen content should be linear in the transition region TR. Forexample, in the transition region TR, the oxygen content may varymonotonically within a specific envelope ENV, as shown in FIG. 19.

Alternatively, the perpendicular magnetization preserving layer PMP maybe formed of a material hardly reacting with oxygen atoms, even duringsubsequent processes or under normal operating conditions. In someexample embodiments, as shown in FIG. 19, the perpendicularmagnetization inducing layer PMI may be formed to have finite oxygencontent, and the perpendicular magnetization preserving layer PMP may beformed to have a substantially infinitesimal oxygen content (forinstance, less than that of the perpendicular magnetization inducinglayer PMI). In some example embodiments, the oxygen content may varyabruptly at an interface between the perpendicular magnetizationinducing layer PMI and the perpendicular magnetization preserving layerPMP. That is, an absolute value of gradient of the oxygen content may begreater at the interface between the perpendicular magnetizationinducing layer PMI and the perpendicular magnetization preserving layerPMP than at the transition region TR.

In other example embodiments, the transition region TR may be formed inthe whole region of the perpendicular magnetization inducing layer PMI.For example, in the graph of FIG. 19, a z-directional gradient of oxygencontent may have a finite non-vanishing value in the whole region of theperpendicular magnetization inducing layer PMI or between the magneticlayer MGL and the perpendicular magnetization preserving layer PMP. Insome example embodiments, the oxygen content of the perpendicularmagnetization inducing layer PMI may be greater at a region adjacent tothe perpendicular magnetization preserving layer PMP than at otherregion adjacent to the magnetic layer MGL.

FIG. 20 is a diagram presented to describe still other aspects of theextrinsic perpendicular magnetization structure.

The formation of the magnetic memory device may further include processsteps (for example, at least one thermal treatment step, a wiring step,and so forth), which will be performed after forming the perpendicularmagnetization inducing layer PMI and the perpendicular magnetizationpreserving layer PMP. As shown in FIG. 20, a thermal energy, which maybe generated during these subsequent process steps or by user's normaloperation, may be supplied to the perpendicular magnetization inducinglayer PMI. This thermal energy may dissociate oxygen atoms from theperpendicular magnetization inducing layer PMI.

However, in the case that the perpendicular magnetization preservinglayer PMP having the low oxygen affinity is formed to cover theperpendicular magnetization inducing layer PMI, it is possible toprevent the dissociated oxygen atoms from diffusing away from theperpendicular magnetization inducing layer PMI. For instance, if thethermal energy is not supplied from outside the magnetic tunnel junctionMTJ, the dissociated oxygen atoms may be restored to its chemicallystable state. Here, in the case that, as the afore-describedembodiments, the perpendicular magnetization preserving layer PMP isformed of a material having a low oxygen affinity, the dissociatedoxygen atoms may be recombined with metal elements constituting theperpendicular magnetization inducing layer PMI, not the perpendicularmagnetization preserving layer PMP. That is, the perpendicularmagnetization inducing layer PMI may be restored to its original statebefore the supply of the thermal energy.

FIG. 21 is an experimental graph exemplarily showing some magneticproperties of MTJ according to example embodiments of inventiveconcepts.

In the experiment, two types of samples were tested to measure aperpendicular anisotropy energy density of the magnetic layer thereinwith respect to a thickness of magnetic layer. In the graph of FIG. 21,a curve denoted by a reference numeral C1 represents experiment dataobtained from the first type of MTJ samples including the extrinsicperpendicular magnetization structure EPMS of FIG. 9, and a pointdenoted by a reference numeral C2 represents an experiment datumobtained from the second type of MTJ sample including the extrinsicperpendicular magnetization structure EPMS of FIG. 13. That is, thefirst corresponds to the extrinsic perpendicular magnetization structureEPMS including a single-layered magnetic layer, and the secondcorresponds to the extrinsic perpendicular magnetization structure EPMSincluding the multi-layered magnetic layers.

In all samples, the tunnel barrier 50 was formed of magnesium oxide(MgO), the magnetic layer MGL and the perpendicular magnetizationinducing layers PMI were formed of CoFeB and Ta—O, respectively, and theperpendicular magnetization preserving layer PMP and the exchangecoupling layer ECL were formed of Ru. The remaining conditions of theexperiment were substantially the same. In the graph of FIG. 21, thehorizontal axis represents a total thickness of the magnetic layersconstituting the extrinsic perpendicular magnetization structure, andthe vertical axis represents a perpendicular anisotropy energy densitymeasured from the magnetic layer.

Referring to FIG. 21, for samples depicted by the reference numeral C1,the magnetic layer of CoFeB had a positive perpendicular anisotropyenergy density, when it was formed to a thickness of about 14 angstromor less. That is, for the extrinsic perpendicular magnetizationstructure EPMS of FIG. 9 or the samples of the first type, the magneticlayer exhibited perpendicular anisotropy in a specific thickness range tof approximately 3 angstrom to approximately 14 angstrom, although themagnetic layer was formed of CoFeB having the intrinsic horizontalmagnetization property.

By contrast, as depicted by the reference numeral C2, even when themulti-layered magnetic layers had a total thickness of about 20angstrom, the perpendicular anisotropy energy density was positive andwas greater than that of the single-layered magnetic layer containingstructure of FIG. 9. This means that, when the magnetic layers of theextrinsic perpendicular magnetization structure are provided as amulti-layered structure, the extrinsic perpendicular magnetizationstructure can be formed to have an increased total thickness without areduction or even with an increase in perpendicular anisotropy energydensity. The increase in the total thickness of the magnetic layersenables to prevent deterioration in thermal stability ofperpendicular-type MTJs, which may occur in MTJs with a thin magneticlayer.

As described above, the layered structures exemplarily shown in FIGS. 9through 17 may serve as part of the magnetic tunnel junctions MTJ1 andMTJ2 shown in FIG. 7 and FIG. 8, respectively. For example, asexemplarily shown in FIG. 22, the upper and lower structures 42 and 41may be realized using two layered structures described with reference toFIGS. 10 and 17, respectively. Here, the layered structure describedwith reference to FIG. 10 may be the extrinsic perpendicularmagnetization structure, while the layered structure described withreference to FIG. 17 may be the intrinsic perpendicular magnetizationstructure IPMS configured to exhibit the SAF property. In this sense,the structure of FIG. 22 corresponds to the MTJ structure of FIG. 7, inwhich the upper structure 42 includes the free layer FRL and the lowerstructure 41 includes the pinning layer PL.

Moreover, as exemplarily shown in FIG. 23, the lower and upperstructures 41 and 42 may be realized using two layered structuresdescribed with reference to FIGS. 10 and 11, respectively. Here, thelayered structure of FIG. 11 may be configured to be greater than thatof FIG. 10 in terms of the total thickness of magnetic layers therein,and as a result, the layered structure of FIG. 11 may serve as a hardlayer or a pinning layer of MTJ. In this sense, the structure of FIG. 23corresponds to the MTJ structure of FIG. 8, in which the upper structure42 includes the pinning layer PL and the lower structure 41 includes thefree layer FRL.

Although the magnetic tunnel junctions according to some exampleembodiments of inventive concepts were exemplarily described withreference to FIGS. 22 and 23, but example embodiments of inventiveconcepts need not be limited thereto.

FIG. 24 is a schematic circuit diagram of a unit cell of a magneticmemory device according to modified embodiments of inventive concepts.

Referring to FIG. 24, a magnetic tunnel junction MTJ according to thepresent embodiments may further include at least one of a lowerelectrode structure 61 disposed below the lower structure 41 and anupper electrode structure 62 disposed on the upper structure 42. Thelower electrode structure 61 may be disposed between the firstinterconnection line 10 and the lower structure 41 or between theselection element 30 and the lower structure 41, and the upper electrodestructure 62 may be disposed between the second interconnection line 20and the upper structure 42.

In some example embodiments, at least one of the lower and upperelectrode structures 61 and 62 may be configured to have asingle-layered structure. In other example embodiments, at least one ofthe lower and upper electrode structures 61 and 62 may be configured tohave a multi-layered structure. In addition, the lower and upperelectrode structures 61 and 62 may include at least one conductive layer(e.g., of metal). But example embodiments of inventive concepts need notbe limited thereto; for instance, in other modified example embodiments,a magnetic tunnel junction MTJ may be configured not to include one ofthe lower and upper electrode structures 61 and 62.

Applications of Embodiments

FIGS. 25 and 26 are block diagrams schematically illustrating electronicdevices including a semiconductor device according to exampleembodiments of inventive concepts.

Referring to FIG. 25, an electronic device 1300 including asemiconductor device according to example embodiments of inventiveconcepts may be used in one of a personal digital assistant (PDA), alaptop computer, a mobile computer, a web tablet, a wireless phone, acell phone, a digital music player, a wire or wireless electronicdevice, or a complex electronic device including at least two onesthereof. The electronic device 1300 may include a controller 1310, aninput/output device 1320 such as a keypad, a keyboard, a display, amemory 1330, and a wireless interface 1340 that are combined to eachother through a bus 1350. The controller 1310 may include, for example,at least one microprocessor, a digital signal process, a microcontrolleror the like. The memory 1330 may be configured to store a command codeto be used by the controller 1310 or a user data. The memory 1330 mayinclude a semiconductor device according to example embodiments ofinventive concepts. The electronic device 1300 may use a wirelessinterface 1340 configured to transmit data to or receive data from awireless communication network using a RF signal. The wireless interface1340 may include, for example, an antenna, a wireless transceiver and soon. The electronic system 1300 may be used in a communication interfaceprotocol of a communication system such as CDMA, GSM, NADC, E-TDMA,WCDMA, CDMA2000, Wi-Fi, Muni Wi-Fi, Bluetooth, DECT, Wireless USB,Flash-OFDM, IEEE 802.20, GPRS, iBurst, WiBro, WiMAX, WiMAX-Advanced,UMTS-TDD, HSPA, EVDO, LTE-Advanced, MMDS, and so forth.

Referring to FIG. 26, a memory system including a semiconductor deviceaccording to example embodiments of inventive concepts will bedescribed. The memory system 1400 may include a memory device 1410 forstoring large amounts of data and a memory controller 1420. The memorycontroller 1420 controls the memory device 1410 so as to read datastored in the memory device 1410 or to write data into the memory device1410 in response to a read/write request of a host 1430. The memorycontroller 1420 may include an address mapping table for mapping anaddress provided from the host 1430 (e.g., a mobile device or a computersystem) into a physical address of the memory device 1410. The memorydevice 1410 may be a semiconductor device according to exampleembodiments of inventive concepts.

The semiconductor memory devices disclosed above may be encapsulatedusing various and diverse packaging techniques. For example, thesemiconductor memory devices according to the aforementioned exampleembodiments may be encapsulated using any one of a package on package(POP) technique, a ball grid arrays (BGAs) technique, a chip scalepackages (CSPs) technique, a plastic leaded chip carrier (PLCC)technique, a plastic dual in-line package (PDIP) technique, a die inwaffle pack technique, a die in wafer form technique, a chip on board(COB) technique, a ceramic dual in-line package (CERDIP) technique, aplastic quad flat package (PQFP) technique, a thin quad flat package(TQFP) technique, a small outline package (SOIC) technique, a shrinksmall outline package (SSOP) technique, a thin small outline package(TSOP) technique, a thin quad flat package (TQFP) technique, a system inpackage (SIP) technique, a multi-chip package (MCP) technique, awafer-level fabricated package (WFP) technique and a wafer-levelprocessed stack package (WSP) technique.

The package in which the semiconductor memory device according to one ofthe above example embodiments is mounted may further include at leastone semiconductor device (e.g., a controller and/or a logic device) thatcontrols the semiconductor memory device.

According to example embodiments of inventive concepts, a magnetictunnel junction may be configured to include an extrinsic perpendicularmagnetization structure. The extrinsic perpendicular magnetizationstructure may include a plurality of magnetic layers and at least oneperpendicular magnetization inducing structure interposed therebetween.Although each of the magnetic layers may be formed to a thicknesssmaller than a critical thickness required for the perpendicularmagnetization property, a total thickness of the magnetically coupledmagnetic layers in the magnetic tunnel junction can be greater than thecritical thickness. The increase in the total thickness of the magneticlayers enables to improve thermal stability of perpendicular-type MTJs.

While example embodiments of inventive concepts have been particularlyshown and described, it will be understood by one of ordinary skill inthe art that variations in form and detail may be made therein withoutdeparting from the spirit and scope of the attached claims.

What is claimed is:
 1. A magnetic tunneling junction device comprising:a first structure including a magnetic layer; a second structureincluding a first extrinsic perpendicular magnetization layer; a secondextrinsic perpendicular magnetization layer; a first non-magnetic layerdisposed on the first extrinsic perpendicular magnetization layer; asecond non-magnetic layer disposed on the second extrinsic perpendicularmagnetization layer; and a third non-magnetic layer disposed on thesecond non-magnetic layer.
 2. The device of claim 1, wherein themagnetic layer of the first structure comprises a ferromagneticmaterial.
 3. The device of claim 2, wherein the ferromagnetic materialis at least one of CeFeB, CoFe, NiFe, CoFePt, CoFePd, CoFePd, CoFeCr,CoFeTb, CoFeGd or CoFeNi.
 4. The device of claim 1, wherein the firstand second extrinsic perpendicular magnetization layer comprises CoFeB.5. The device of claim 1, wherein at least one of the first and secondnon-magnetic layers comprise at least one of Ta, Ti, U, Ba, Zr, Al, Sr,Hf, La, Ce, Sm, Mg, Th, Ca, Sc, or Y.
 6. The device of claim 1, whereinthe third non-magnetic layer comprises at least one of Ru, Rh, Pd, Ag,Os, Ir, Pt, or Au.
 7. The device of claim 1, wherein the oxygen affinityof the third non-magnetic layer is less than the oxygen affinity of thesecond non-magnetic layer.
 8. The device of claim 1, wherein the firststructure further comprises an exchange coupling layer disposed betweentwo magnetization layers.
 9. The device of claim 1, further comprising atunnel barrier layer between the first structure and the secondstructure.
 10. The device of claim 9, wherein the tunnel barrier layeris thicker than the second non-magnetic layer.
 11. An electronic device,comprising: a bus: a wireless interface configured to transmit data toor receive data from a wireless communication network connected to thebus; an I/O device connected to the bus; a controller connected to thebus; and a memory including a semiconductor device including themagnetic tunneling junction device of claim 1, connected to the bus,configured to store command code to be used by the controller or userdata.
 12. A semiconductor memory device comprising: a substrate; a firststructure including a magnetic layer, the first structure disposed onthe substrate; a tunnel barrier layer disposed on the first structure; asecond structure disposed on the tunnel barrier layer, the secondstructure including: a first extrinsic perpendicular magnetizationlayer; a second extrinsic perpendicular magnetization layer; a firstnon-magnetic layer disposed on the first extrinsic perpendicularmagnetization layer; a second non-magnetic layer disposed on the secondextrinsic perpendicular magnetization layer; and a third non-magneticlayer disposed on the second non-magnetic layer, wherein the oxygenaffinity of the third non-magnetic layer is less than the oxygenaffinity of the second non-magnetic layer.
 13. The device of claim 12,wherein the magnetic layer of the first structure comprises aferromagnetic material.
 14. The device of claim 12, wherein theferromagnetic material is at least one of CeFeB, CoFe, NiFe, CoFePt,CoFePd, CoFePd, CoFeCr, CoFeTb, CoFeGd or CoFeNi.
 15. The device ofclaim 12, wherein the first and second extrinsic perpendicularmagnetization layer comprises CoFeB.
 16. The device of claim 12, whereinat least one of the first and second non-magnetic layers comprise atleast one of Ta, Ti, U, Ba, Zr, Al, Sr, Hf, La, Ce, Sm, Mg, Th, Ca, Sc,or Y.
 17. The device of claim 12, wherein the third non-magnetic layercomprises at least one of Ru, Rh, Pd, Ag, Os, Ir, Pt, or Au.
 18. Thedevice of claim 12, wherein the first structure further comprises anexchange coupling layer disposed between two magnetization layers. 19.The device of claim 12, wherein the second extrinsic perpendicularmagnetization layer is in direct contact with the second non-magneticlayer.